Medicare Supplement (Medigap) Explained: How It Works in 2026
Quick answer: Medicare Supplement insurance — also called Medigap — is a private insurance policy that works alongside Original Medicare (Parts A and B) to cover the coinsurance, copays, and deductibles Original Medicare leaves behind. Medigap plans are standardized by letter (Plan G, Plan N, etc.), so the coverage is identical no matter which company sells it — only the premium and customer service differ. In 2026, Plan G averages around $220/month at age 65, and Plan N around $168–$171/month, though rates vary significantly by carrier, age, gender, tobacco use, and location.
What Is Medicare Supplement (Medigap) Insurance?
Original Medicare covers a large share of your healthcare costs, but not all of it. Part A has a $1,736 hospital deductible in 2026, and Part B leaves you responsible for 20% coinsurance on most services with no cap on how high that can add up over a year. Medigap exists specifically to fill those gaps — it doesn't replace Medicare, it works alongside it. Medicare pays its share of an approved claim first, and your Medigap policy picks up some or all of what's left, depending on which plan letter you have.
Common question — is Medigap the same as Medicare Advantage? No. Medigap works with Original Medicare and lets you see any provider nationwide who accepts Medicare. Medicare Advantage replaces how your benefits are delivered through a private insurer's network. You cannot have both at the same time.
How Medigap Plans Are Standardized
Every Medigap plan is labeled with a letter — A, B, D, G, K, L, M, or N are the most commonly sold today (Plans C, F, and high-deductible F are closed to anyone newly eligible for Medicare on or after January 1, 2020, though people who already had them can keep them). The federal government standardizes the benefits for each letter, meaning a Plan G from one company covers exactly the same things as a Plan G from another company. What differs between companies is the premium, financial strength, customer service, and how the premium is priced over time.
Insurance companies generally price Medigap premiums one of three ways:
Community-rated: Everyone pays the same premium regardless of age; rates rise only with inflation or overall claims experience.
Issue-age-rated: Your premium is locked in based on your age when you first buy the policy, and tends to stay lower over time.
Attained-age-rated: Your premium starts lower but increases as you get older, often becoming the most expensive option long-term.
Common question — will my Medigap premium go up every year? Almost certainly, to some degree — inflation and claims trends affect nearly all Medigap pricing along with your age. But how much and how predictably it rises depends heavily on which pricing method your carrier uses, which is worth asking about before you enroll, not after.
Plan G and Plan N: The Two Most Popular Medigap Plans in 2026
Plan G is currently the most popular choice for new Medicare enrollees. It covers nearly everything Original Medicare doesn't, with the single exception of the annual Part B deductible ($283 in 2026), which you pay out of pocket once per year. The average premium at age 65 is around $220/month in 2026, though it varies significantly by carrier and location.
Plan N is the second most common choice. It costs less on average — roughly $168–$171/month at age 65 — but requires small copays for office visits and emergency room visits, and doesn't cover Part B excess charges (the amount a provider can legally charge above Medicare's approved rate, in states that allow it). Plan N tends to suit people who don't see specialists often and are comfortable with modest per-visit copays in exchange for a lower monthly premium.
High-Deductible Plan G offers the exact same coverage as standard Plan G, but at a lower premium (often around $60/month) in exchange for a $2,950 annual deductible in 2026 that you pay before the plan starts covering costs. This can be a strong fit for people who are healthy, have savings set aside, and want protection against a worst-case year without paying for first-dollar coverage they may not use.
Common question — is Plan G or Plan N better? Neither is universally better — Plan G offers more predictable costs with a higher premium, while Plan N offers a lower premium in exchange for small, predictable copays. The right choice usually comes down to how often you expect to use care and how you'd rather budget for it: a higher fixed monthly cost, or a lower monthly cost with occasional per-visit charges.
When Can You Enroll in a Medigap Plan?
Unlike Medicare Advantage or Part D, there is no annual open enrollment period for Medigap. Timing matters far more here than with other parts of Medicare:
Medigap Open Enrollment Period: A one-time, 6-month window that starts the month you're both 65 or older and enrolled in Part B. During this window, insurers must sell you any Medigap policy they offer, at their best available rate, regardless of your health history.
After that window closes, insurers in most states are legally allowed to use medical underwriting — meaning they can charge you more, add exclusions, or deny coverage entirely based on your health history, unless you qualify for a guaranteed issue right (such as losing other coverage involuntarily).
Guaranteed issue rights can also apply in specific situations — for example, if your Medicare Advantage plan leaves your area, or if you're within your first 12 months of trying Medicare Advantage and decide to switch back to Original Medicare (a "trial right").
A note for Colorado residents: Some states have adopted a "birthday rule" that lets existing Medigap policyholders switch plans once a year around their birthday without medical underwriting. As of 2026, Colorado is not currently one of those states, so outside of your initial 6-month window or a qualifying guaranteed issue event, switching or shopping Medigap carriers typically requires answering health questions. Because rules like this can change with new state legislation, it's worth confirming current Colorado requirements before making a switch.
Common question — what happens if I miss my Medigap Open Enrollment Period? You can still apply for a Medigap policy later, but insurers can require medical underwriting and may charge more, add a waiting period for pre-existing conditions, or decline coverage — unless a guaranteed issue right applies to your situation. This is one of the most consequential timing decisions in all of Medicare, and it's worth getting right the first time.
Is Medigap Right for You?
A Medicare Supplement plan tends to be a strong fit if you:
Want the freedom to see any doctor or specialist nationwide who accepts Medicare, without referrals
Prefer predictable monthly costs over variable out-of-pocket bills
Travel frequently, split time between states, or want coverage that isn't tied to a local network
Are within your 6-month Medigap Open Enrollment window, when acceptance is guaranteed regardless of health
It may be worth comparing against Medicare Advantage instead if you:
Want built-in dental, vision, and hearing benefits without paying an additional premium
Are comfortable using a defined network of doctors
Would rather pay a lower monthly premium and accept some network restrictions
Because Medigap pricing can vary by hundreds of dollars a month between carriers for the exact same benefits, and because timing your enrollment correctly can mean the difference between guaranteed acceptance and medical underwriting, this is one of the areas where a side-by-side comparison with a licensed local advisor tends to save real money.
Frequently Asked Questions
What is Medicare Supplement insurance? Medicare Supplement insurance, or Medigap, is a private policy that works alongside Original Medicare to help cover coinsurance, copays, and deductibles that Medicare doesn't pay. Plans are standardized by letter, so benefits are identical between carriers offering the same plan letter.
What is the difference between Medigap Plan G and Plan N? Plan G covers nearly all Medicare cost-sharing except the annual Part B deductible, and has a higher average premium. Plan N has a lower average premium but requires small copays for office and ER visits and doesn't cover Part B excess charges.
Can I switch Medigap plans at any time? Not without restrictions. Outside your one-time 6-month Medigap Open Enrollment Period (starting when you're 65+ and enrolled in Part B) or a qualifying guaranteed issue event, insurers can require medical underwriting before approving a new policy or switch.
Do I need Medicare Part D if I have a Medigap plan? Yes. Medigap plans do not include prescription drug coverage — you'll need a separate, standalone Part D plan alongside your Medigap policy.
How much does Medicare Supplement insurance cost in 2026? Costs vary by plan letter, carrier, age, gender, tobacco use, and location. As general reference points for 2026, Plan G averages around $220/month at age 65, Plan N around $168–$171/month, and High-Deductible Plan G around $60/month with a $2,950 deductible.
Is Plan F still available? Plan F is closed to anyone newly eligible for Medicare on or after January 1, 2020. If you already had Plan F before that date, you can keep it, but you cannot enroll in it for the first time today.
Compare Your Medigap Options in Grand Junction
The same Medigap plan letter can cost hundreds of dollars a month more with one carrier than another for identical benefits — and getting your enrollment timing right matters just as much as the plan you choose. Schedule a free, no-obligation consultation to compare your real options.
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This page is for educational purposes and does not constitute a recommendation of any specific plan or carrier. We are not connected with or endorsed by the U.S. government or the federal Medicare program.